Why are you not useing forumotions option for word censoring?I dont see why it would have to in any codeing since forumotion already provide this option in the acp? plus you are useing phpbb3 so unless you are able to put the script/code in your forum description or homepage announcement then you would not be able to use it?

Depending on what you find you may be able to use in the two places i said.But of course you would have to test it and make sure it dose not conflict with other things on your forum..Because time to time we get a lot of people that use phpbb3 and add codes that effect other things on their forum. So you have to be sure you test it and it is working properly.